Metal-oxide-semiconductor (MOS) transistor is one of the most important components in modern integrated circuits (ICs). The base structure of a MOS transistor includes a semiconductor substrate, a gate structure formed on the surface of the semiconductor substrate, and a source region and a drain region formed in the semiconductor substrate on the two sides of the gate structure. In addition, the gate structure includes a gate dielectric layer formed on the surface of the semiconductor substrate and a gate electrode layer formed on the gate dielectric layer.
With the development of semiconductor technology, the feature size of semiconductor devices continuously decreases, and the controllability of traditional planar MOS transistors on channel current tends to be insufficient, causing severe leakage current. Fin field-effect-transistor (Fin-FET) is an emerging multi-gate device. Generally, a Fin-FET includes a fin structure protruding from the surface of a semiconductor substrate, a gate structure covering a portion of the top and the sidewall surfaces of the fin structure, and a source region and a drain region formed in the fin structure on the two sides of the gate structure.
However, the electrical performance of the Fin-FETs fabricated by existing methods may still need to be improved. The disclosed Fin-FET devices and the fabrication methods are directed to solve one or more problems set forth above and other problems in the art.